This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Bacteriophage Syn 5 infects Synechococcus, a cyanobacterium that plays an important role in the Carbon and Oxygen cycles on Earth. As such it is of interest to ecologists and oceanographers, who are just realizing the importance of oceanic bacteria and their parasites. We are interested in the structural adaptations that they have made to their environment.